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CSLB C-10 Electrical Contractor practice questions

210 free questions with answers and explanations.

Practice test
  1. 201.A commercial client requires a new 208V, 3-phase, 40A feeder for a motor load. The feeder will run 150 feet from the panel to the motor. The conductor insulation type is THHN, and the maximum allowable voltage drop is 3%. What is the minimum AWG copper conductor size required?Planning and Estimating
  2. 202.An electrician is reviewing blueprints for a new commercial building. The general notes specify that all conductors for branch circuits are to be rated at 75°C. For a 120V, 20A general-purpose branch circuit, what is the minimum allowable ampacity of the conductors before applying any adjustment or correction factors, assuming copper conductors?Planning and Estimating
  3. 203.A client requests a new 20A, 120V branch circuit to an outdoor shed. The circuit will be protected by a GFCI circuit breaker. What is the minimum burial depth required for a Type UF cable directly buried under a driveway, if no other protection is provided?Wiring Methods and Materials
  4. 204.An electrical contractor is preparing a material takeoff for a new commercial office building. The blueprints indicate a symbol for a specific type of receptacle: a circle with two horizontal lines through it, and a 'WP' next to it. What does this symbol represent?Planning and Estimating
  5. 205.An electrician is installing a new 120V, 20A general-purpose receptacle branch circuit in a commercial office. The circuit will consist of 10 duplex receptacles. According to the NEC, what is the minimum calculated load for these receptacles for the purpose of service or feeder calculations?Planning and Estimating
  6. 206.A client is planning a new commercial office building. The blueprints specify a 208V, 3-phase, 4-wire service with a total general lighting load of 30,000 VA and 15,000 VA of receptacle loads. All loads are considered non-continuous. What is the minimum calculated demand load for the general lighting and receptacle loads, before applying any demand factors for receptacles?Planning and Estimating
  7. 207.A new industrial motor control center requires a feeder connection. The feeder conductors are 3/0 AWG THHN copper. The circuit breaker protecting the feeder is rated for 200A, and the terminals on the motor control center are listed for 75°C. What is the maximum allowable ampacity for these conductors, considering the termination temperature limitation?Wiring Methods and Materials
  8. 208.A residential service entrance requires a grounding electrode conductor (GEC) to connect to a concrete-encased electrode (Ufer ground). The service entrance conductors are 4/0 AWG copper. What is the minimum size copper GEC required for this installation, according to NEC Table 250.66?Wiring Methods and Materials
  9. 209.A pilot light for an industrial control panel must be installed in a hazardous location where flammable gases are present during normal operations. Which wiring method is generally required for such a location, according to NEC Article 500?Wiring Methods and Materials
  10. 210.A client requests a new dedicated 20-ampere, 120-volt branch circuit for a single-phase, hermetic refrigerant motor-compressor. The motor-compressor has a nameplate rated-load current (RLC) of 15 amperes and a branch-circuit selection current (BCSC) of 18 amperes. What is the minimum continuous current rating required for the branch-circuit overcurrent protective device (OCPD)?Equipment and Installation